Signaling system for railroads



Sept. 22, 1931. o. H. DICKE SIGNALING SYSTEM FOR RAILROADS Filed Oct. 15, 1930 FIG.2.

FIG.3.

lNVENTO BY M a MMM ATTORNEY v 35 resistance.

Patented Sept. 22, 1931 NE'EED STATEE PATENT FFEfiE OSCAR H. DICKE, OF ROCHESTER, NEW YORK, ASSIGNGR TO GENERAL RAILWAY SIGNAL COMPANY, OF ROCHE TEB, NEWV YORK SIGNALING SYSTEM FQR RAILROADS Application filed. Qctoher 15, 1930.

upon the entrance of a train under extremely dry or high resistance ballast conditions (low ballast leakage), and that the track relay may assume its deenergized danger position even though there is no train in the block if the ballast leakage is very high, that is, the ballast resistance between track rails is very low.

In view of the foregoing and other important considerations, it is proposed in accordance with the present invention to so arrange the track circuit that the track circuit source and the track relay are located at the same end of the track section, with the track relay of such construction that it will not respond to the track circuit source until the current has been modified by suitable means located. at the opposite end of the track circuit. This expedient has been resorted to, among other things, in order to reduce the potential across the track rails of the track circuit to an eX- tremely low value, so that very little, if any, change in the operation of the track circuit is experienced due to variation of the ballast Furthermore, the current that actually flows through the ballast resistance will be of the original and un-modified kind, so that it will have no effect on the track relay.

Other objects, purposes and characteristic features of the present invention will in part be pointed out hereinafter and will in part be obvious from the accompanying drawings.

In describing the invention in detail refer- 4:5 ence will be made to the accompanying drawings, in which Fig. 1 shows one embodiment of the present invention in which an alternating current is used as the track circuit source, which 59 current 1s modified by a rectifier;

Serial No. 488,899.

Fig. 2 shows a modified construction in which a direct current source is used, which Structure F 2'9. 1.

Referring to Fig. 1 of the drawings, the track rails 1 have been shown divided into blocks by insulating joints 2, of which the block I and the adjacent ends of two other blocks H and J only have been shown. Since the apparatus of each of the blocks is the same, the apparatus of one block will only be described, like parts of each block being designated by like reference characters having distinctive exponents. In the particular embodiment of the invention shownin Fig. 1, an alternating current source comprising a transformer T included in series with a. threeposition direct current polar relay DC, is connected across the track rails 1 of the block, the normal direction of trafiic being from left to right as indicated by the arrow. At the exit end of the block I a rectifier B is connected across the track rails through the medium of a pole changer switch PC, so that this rectifier R is poled in the track circuit in one direction so long as the signal S assumes either the clear or caution position, but is poled in the reverse direction when the signal S assumes the stop position. The signal S is of course controlled through the medium of the clear wire d and the caution wire at which wires are energized through the medium of polar contacts of the track relay DC,

all as well understood by those skilled in the.

art of railway signaling.

Operation Fig. 1

Under normal conditions,thatiswhenthere are no trains in the block I, the track relay DC is held in its normal right hand clear position in response to current supplied by one wave of a certain polarity from each cycle of the alternating current derived from the source A and flowing through the following circuit :-beginning at the secondary winding of the transformer T, wire 10, winding of the relay DC, wire 11, track rail 1, wire 12, contact 13, wire 14, rectifier R, wires 15 and 16, contact 17 of the pole changer switch PC, wire 18, track rail 1, wire 19 back to the secondary winding of the transformer T. Obviously, if the signal S at the entrance to the block J should be moved to its danger posi tion as by reason of a train in said block, the pole changer PC would assume its dotted position, thereby reversing the rectifier R in the circuit just traced, and thereby causing direct current to flow through the track relay DC in the reverse direction, thus operating this relay DC to its left hand position, efiecting opening of the clear circuit CZ and closure of the caution circuit 0a, and elfecting operation of the signal S to the caution position.

Let us now assume that a train moving from left to right moves from the block H into the block I, thereby shunting the rectifier R out of the circuit heretofore traced. Vith the rectifier R shunted out of the circuit alternating current only will flow through the rack relay DC, and since this track relay DC is so constructed as not to respond to alternating current this track relay DC will assume its neutral pendent position, thereby opening both the clear circuit cl and the caution circuit ca and effecting operation of the signal S to its danger stop position.

By reason of the fact that the track relay DC is included in series with the secondary winding of the transformer T the impedance drop due to the impedance of the relay DC will cause the voltage across the track rails 1 to be the difference between the voltage of the transformer T and the impedance drop of the relay DC, so that if the rectifier R is of rather low resistance, for current flow in a particular direction, the potential across the track rails 1 of the block I will be comparatively low for the particular waves of alternating current which readily flow through the rectifier R. In other words, the potential across the track rails is extremely low, and for this reason the flow of current through the ballast is very low, and the operating margin of the track circuit is materially improved in spite of extreme variations in ballast resistance.

Structure Fig. 2

magnet, may be an interrupter of the motor operated type includlng a motor 9 and shown in Fig. 2, or may be an interrupter having a 'contact 23 operated by an electromagnet 24 Operation F 2 Under normal conditions, that is with the block I unoccupied, the track relay AC will be energized by alternating current derived from the secondary winding of the transformer-TF, which alternating current is derived from the pulsating current flowing in primary of the transformer and in the track circuit of the block I and including the track rails 1 and the interrupter IR. Let us now assume that there is a train moving from left to right in the normal direction of traffic from the block H into the block 1 As soon as this train treads upon the track circuit of the block I the interrupter IR will be shunted out, so that only uniform and substantially constant direct current fiows through the primary winding of the transformer TF, as a result of which practically no alternating current flows in the secondary winding and the track relay AC, so that this track relay AC is deenergizcd, thereby operating the signal S to its stop position. The transformer TF is used primarily for filtering purposes, in that it prevents continuous direct current in the track circuit from energizing the relay AC. For reasons already explained in connection with the embodiment of the invention shown in Fig. 1, the potential across the track rails in Fig. 2 is also extremely low as Compared with the potential of the track battery 20, so that the leakage current flowing through the ballast resistance is correspondingly low and the variable effect of this ballast resistance has a correspondingly smaller effect upon the function of the track circuit under consideration, furthermore the current flowing through the ballast is direct con tinuous current and does not affect the relay AC.

Having thus shown and described several specific embodiments of the present invention, it is desired to be understood that the particular embodiments of the invention illustrated in the drawings have not been selected for the purpose of illustrating the scope of the invention nor have they been selected to show the exact construction preferably employed in practicing the invention, but have been selected to facilitate description of. the invention as well as its operating features and characteristics, and it is further desired to be understood that various changes, modifications and additions may be made to adapt the invention to the particular problem encountered in practicing the same, all without departing fromthe spirit or scope of the invention or the idea of means underlying the same, except as demanded by the scope of the following claims.

What I claim as new is 1. In combination, a section of railway track isolated from the remaining track by insulating joints, a track circuit for said section including a source of current of one character and an electro-responsive device responsive only to current of a different character connected in series across the track rails at one end of said section, and means connected across the track rails at the other end of said section for changing the current derived from said source to a current of said difierent character.

2. In combination, a section of railway track isolated from the remaining track by insulating joints, a track circuit for said section including a source of current of one character and an electro-responsive device responsive only to current of another character connected in series across the track rails at one end of said section, and means connected across the track rails at the other end of said. section for changing the current derived from said source to a current of said another character.

3. In combination, a section of railway track isolated from the remaining track by insulating joints, a track circuit for said section including a source of direct current and an electro-responsive device responsive only to pulsating or alternating current connected in series and across the track rails at one end of said section, and means connected across the track rails at the other end of said section for changing said direct current to pulsating current.

4:. In combination, a section of railway track isolated from the remaining track by insulating joints, a track circuit for said section including a source of alternating current and an electro-responsive device responsive only to direct current connected in series across the track rails at one end of said section, and means connected across the track rails at the other end of said section for changing said alternating current to direct current.

5. In combination, a section of railway track isolated from the remaining track by insulating joints, a track circuit for said section including a source of current of one character and an electro-responsive device responsive only to two distinctive currents each of another character connected in series across the track rails at one end of said section, and means connected across the track rails at the other end of said section for changing the current derived from said source to one or the other of said distinctive currents of said another character.

6. In combination, a section of railway track isolated from the remaining track by insulating oints, a track circuit for said section including a source of alternating current and an electro-responsive device responsive only to direct current of one polarity or the other and connected in series across the track rails at one end of said section, and means connected across the track rails at the other end of said section for changing said alternating current to direct current of one polarity or the other.

7. In combination, a section of railway track isolated from the remaining track by insulating joints, a track circuit for said section including a source of current of one character and an electro-responsive device responsive only to current of a different character connected in series across the track rails at one end of said section, means connected across the track rails at the other end of said section for changing the current derived from said source to a current of said different char acter, and a contact included in series with said means and controlled in accordance with traflic conditions in advance of said section! 8. In combination, a section of railway track isolated from the remaining track by insulating joints, a track circuit for said sectionincluding a source of current of one character and an electro-responsive device responsive only to current of another character connected in series across the track rails at one end of said section, means connected across the track rails the other end of said section for changing the current derived from said source to a current of said another character, and a contact included in series With said means and controlled in accordance with trafiic conditions in advance of said section.

9. In combination, a track isolated from the remaining track by insulating joints, a track circuit for said section including a source oi alternating current and an electroresponsive device responsive only to direct current connected in series across the track rails at one end of said section, and a rectifier connected across the track rails at the other end of said section for changing said alternating current to uni-directional current.

10. In combination, a section of railway track isolated from the remaining track by insulating joints, a track circuit for said section including a source of alt rnating current and an electro-responsive device responsive only to direct current connected in series across the track rails at one end of said section, a rectifier connected across the track rails at the other end of said section for changing said alternating current to uni-directional current, and a contact included in series with said rectifier and controlled in accordance with trafiic conditions in advance of said section.

11. In combination, a section of railway track isolated from the remaining track by insulating joints, a track circuit for said section including a source of direct current and an electro-responsive device responsive only to pulsating or alternating current connected in series and across the track rails at one end of said section, and a current interrupter connected across the track rails at the other end of said section for changing said direct current to pulsating current and operated by the current flowing in the track rails.

12. In combination, a section of railway track isolated from the remaining track by insulating joints, a track circuit for said section including a source of direct current and 1 an electro-responsive device responsive only to pulsating or alternating current connected in series and across the track rails at one end of said section, and a current interrupter connected across the track rails at the other end of said section for changing said direct current to pulsating current and consisting of an electro-magnet in series with a contact thereof closed when said eiectro-magnet is deenergized.

13. In combination, a section of railway track isolated from the remaining track by insulating joints, a track circuit fer said sec tion including source of direct current and the one winding of a transformer in series connected across the track rails at one end of said section, a relay connected across the secondary winding of said transformer, and means connected across the track rails at the other end of said section for changing said direct current to pulsating current.

14. In combination, a section of railway track isolated from the remaining track by insulating joints, a track circuit for said section including a source of direct current and an electro-responsive device responsive only to pulsating or alternating current connected in series and across the track rails at one end of said section, and traflic controlled means connected across the track rails at the other end of said section for changing said direct current to pulsating current.

15. In combination, a section of railway track isolated from the remaining track by insulating joints, a track circuit for said section including a source of current of one character and an elect-ro-responsive device responsive only to two distinctive currents each of another character connected in series across the track rails at one end of said section, and means controlled by trafiic conditions in ad vance and connected across the track rails at the other end of said section for changing the current derived from said source to one or the other of said distinctive currents of said an other character.

16. In combination, a section of railway track isolated from the remaining track by insulating joints a track circuit for said section including a source of alternating current and an electro-responsive device responsive only to direct current of one polarity or the other and connected in series across the track rails at one end of said section, and means controlled in accordance with traflic condi-- OSCAR H. DICKE. 

